Ford 7.3L gas power numbers

carringb wrote:
Torque gets you going, HP tells you how fast you can go.

Torque can be multiplied. HP can't.

At see level, if Ford made a 440 hp version of the 7.3L, it would pull hills at exactly the same speed as the current 6.7L. Because the 6.7L makes more torque, it will accelerate a heavy load quicker than the 7.3L, unless Ford puts in much lower rear gears, to make the Tractive Force (engine torque * transmission reduction ratio * differential reduction div by tire radius) equivalent.

This new engine has some design features to allow for future power increases. My suspicion is that whenever the 6.7L gets a hp bump, this motor will too. They'll reserve the top HP rating for their premium (i.e. high margin) 6.7L, while keeping the 7.3L numbers competitive with other gas motors.

That is true if the torque converter was locked. The torque converter also multiplies torque when unlocked, but not horsepower. In fact you loose anywhere between 10-40% of engine horsepower when the TC isn't locked. Most people do not take this into account and is why I say it is not just about how much that is important, but when.

If the 10 speed gearing with this 7.3L is the same as the one in the F150 and it comes with a 3.73 rear gear, then the third gear is the farthest you can go with the TC being locked the closest to max hp and torque while maintaining a reasonable towing speed. In 2nd, peak power(5,500 rpm) is achieved at 50 mph, in third it is 69 mph, and 4th is 84 mph. You will traveling too fast past the trucks governor to be locked at peak power in any gear past this.

How much horsepower is lost when unlocked depends on many variables such as the efficiency and stall speed of the converter in stock form. The fluid's viscosity also has a major impact on how much power is getting past the TC is as well. Generally a higher viscosity(to a point) means it is more efficient while a lower viscosity will make it less efficient. The fluid looses viscosity the hotter it gets(towing situations) and over time as it breaks down.

Since diesels generally peak at much lower rpms, their power and torque is usable in more gears and at more speeds with the TC locked sending full engine power past the TC.